1. Technical Field
The present invention relates to an adhesive film for polarizing plates, a polarizing plate including the same, and an optical display including the same.
2. Description of the Related Art
Polarizing plates are provided on upper and lower sides of a liquid crystal display (LCD) panel and may be bonded to the LCD panel via an adhesive film for polarizing plates. The polarizing plate shrinks or expands under severe conditions such as high temperature (for example, 85° C.) and high humidity. If the adhesive film for polarizing plates exhibits poor durability, the polarizing plate peels off of the LCD panel and thus suffers from failures such as detachment, bubbling and the like, and can also cause light leakage due to a difference in dimensional change between the polarizing plate and the adhesive film for polarizing plates. Thus, the adhesive film should have high durability and light leakage suppression properties, which can be accomplished by controlling or mitigating stress due to shrinkage or expansion of the polarizing plate. In addition, the adhesive film should exhibit good re-peeling capability to enable reworking which may be necessary due to a foreign substance or a process failure during attachment of the polarizing plate including an adhesive layer to the LCD panel. The adhesive film should also exhibit good cuttability and a short aging period to enable quick use after coating an adhesive in order to improve productivity of the polarizing plate.
Although an over-cured hard type adhesive film for polarizing plates is highly crosslinked after aging and thus suppresses light leakage, the over-cured hard type adhesive film can suffer from detachment or wrinkling at the edges of the polarizing plate due to low initial adhesion. There is a trade-off between durability and light leakage depending on the amount of cross-linking agent. If the amount of the cross-linking agent is reduced, the polarizing plate suffers from severe light leakage despite good durability due to low crosslinking, and if the amount of the cross-linking agent is increased, the polarizing plate can have deteriorated durability although light leakage is suppressed.